Plate lifting clamp



Jan- 15, 1946. E. M. GARDNER 2,393,101 v PLATE LIFTING CLAMP Filed April 14, 1945 Trap/YE? Patented Jan. 15, 1946 PLATE LIFTING CLAMP Edward Merrill Gardner, Brooklyn,V N. Y., as-

signor to Merrill Brothers, New York, N. Y., a corporation of: New York Application April 14, 1945, Serial No. 588,363

6 Claims.

l This invention relates to a new and improved plate lifting clamp having a shackle of new and improved design. The plate Vlifting clamp is utilizable for lifting steel plates, structural elements presenting a thin lifting edge, and other members, such as steel containers or barrels, which may have a relatively thin edge for the reception of .a lifting clamp.

More particularly, my invention relates to a newandimproved plate lifting clamp, operable by a vertically applied lifting force, which is espe-v cially adapted for lifting sheet metal plates and similar thin-edged metallic members from either a'horizontal oivertical position, and, in fact, from anyposition intermediate between horizontal and` verticalin whichthe plates or elements happen tobe positioned. It is also especially useful for pulling out a horizontal plate from under a pile of plates by tilting the entire pile above the platey being extracted. It is especially suitable for use in lowering plates into the holds of ships,

the working parts being protected from contact with hatch coamings Yor other obstructions. It is compact, light weight for itscapacity, and rugged in construction, positive and instantaneous in its gripping action, and so designed that the greater the load to be lifted, the rmer is the grip b y whichthe load is retained in the clamp. Also it will not release its grip if by inadvertence the lifting pressure is relaxed. l

In manufacturing and materials-.handling operations, in the construction of structural steel structures, and in many storage and assembly operations, it is frequently necessary to lift relatively heavy sheet metal plates and transport them to a new position or location. Steel plates are frequently stored in racks, either on their edges (vertically), or in piles, with the plates lying ilat in a horizontal position. While plate' lifting clamps are nowv available, and have been used for lifting relatively thin-edged structural elements or metallic containers, there has not been heretofore available a satisfactory lifting clamp of simple compact design, rugged construction, positive and instantaneous in its lifting action, vwhich would lift thin-edged members by means of a pull or tension applied to the end of the lifting clamp regardless of whether the elements to be lifted are stacked in a horizontal or vertical-position, or buried under a pile of other of the clamp. Y Other plate lifting clamps are especially adapted for lifting thin-edged inembers from a vertical (position, as, for example, lifting plateswhich are supported on their edges. While some clamps now available will liftfrom both horizontal and vertical positions,` they do not have the simplicity of mechanical movement, nor do they supply the powerful lifting moment when lifting plates from a horizontal position, characteristic of my new and improved lifting clamp. There has not previously been available a compact, rugged, relatively'light weight,j positive-acting plate lifting clamp of this type, characterized by simple, smooth mechanical movements, which will function to lift plates or similar thin-edged elements from both the horizontal and vertical positions, and, in fact, from any position therebetween, bymeans of a lifting force or tension applied to the clamp shackle.

Itis one of the objects of this invention topro# vide a lifting clamp embodying a shackle of a new and novel design, which clamp will function both to lift plates 'from a horizontal position wherein they are stacked on top of one another, and from a vertical position in which the plates may be supported on their edges,`by means of'a lifting force applied vertically at theen'd of the shackle. y y:

Another object of this invention is to provide a clamp of this type suitable for lifting plates ariel similar thin-edged elements from both horizontal and vertical positions, and from any angular position therebetween in which the elements are stacked or positioned, by means of a vertical lifting force applied at the end of the clamp shackle. A further object of this invention is to provide a lifting clamp of the type described which will be of relatively simple construction; having few operating parts, and of simple mechanical 'motions, thereby having but little tendency to get out of order or torequire adjustment. Additional objects include providing a lifting clamp of compact and rugged, yet relatively light, construction, which is so designed that the gripping force is instantaneous and positive, and of a type such that the heavier is the load to be lifted, the firmer is the grip. It is also an object to provide a lifting clamp so designed as to insure safety, so that if the plate inadvertently rests upon some object or rests upon the iioor the grip will not Vbe released, but will hold firmly untilmanually releasedvby breaking apart the interlocked plate serratlons between the stationary jaw teeth arid the rotating cam teeth. These objects of my invention, as wellas others, will be apparent from lifted by means of a vertical pull or lifting force applied at the end of the shackle.

Fig. 2 is a View in elevation of the improved plate lifting clamp of Fig. l, this clamp being shown in the position it assumes when steel plates stacked horizontally, as one on top of the other,

I tends to rotate around its pivot I2, thereby forcing connecting links I1 downwardly and cans.. ing the cam I4 to rotate around the pivot II in a clockwise direction. The cam I4 is so shaped that, upon its rotation in the clockwise direction, the plate 9 is pressed tightly and securely held between the gripping teeth or serrations I4a of the cam I4 and the gripping pads lli in the slot l. The gripping edges Illa of cam I4 may be provided with serrations, as shown, to prevent slipping. It is evident that the heavier the load, and

are lifted by means of a vertical lifting force applied to the clamp; and

Fig. 3 is a cross-sectional view through the clamp taken on the line 3-3 of Fig. 1.

Referring more particularly Vto the drawing, the operating elements comprising my invention may be venclosed a casingor housing which is preferably'made of forged and tempered steel. The casing 4 includes'side members 5 and 6 which are out away to provide aslotted portion I to receivethe plate -9 or other thin-edged element to be lifted. As shown in Figs. l and 3, there are provided in the slotted portion 'I of the casing 4 one or more serrated tempered gripping pads IIJ, forming an abutment portion vof the casing, against which the plate is pressed and securely held during the lifting operation. These gripping pads may be formed integrally with the casingr 4. The serrationsform a,V gripping surface and aid in preventing the plates from slipping during the gripping and lifting operation, and, since they are stationary, form a positive lock with-serrations on cam I4 to prevent vtoo easy release.

Headed pivot pins or bolts II and I2 serve as bearings for the operating elements described below.' `These pivot pins or bolts may extend entirely through the casing, and may be retained by cotter pins (not shown), in holes Ila and I2a atone end ofthe pins or bolts. They may also be retained in the casing 4 in some other manner, such as by upsetting the ends of the bolts.

. The pivot pins or bolts II and i2 serve, respectively, as axes of rotation for cam I4 and radius linlr.` I5, which are positioned within the casing 4. Connecting links I'I are also positioned within thecasing 4, between cam I4 and radius link I5, being pivoted at I9 to the cam I4 andat 2| to one end of the radius link I5. The other end of the radius link I5 is pivoted at 23 to one end of the shackle 24, part of which extends outside of the casing Ii, and an intermediate part of which is provided with a projection 25 having the function described below. The projecting end` of the shackle 24 may be provided with an aperture 26, through which may be passed lifting hook 28, at theend of which a vertical lifting force may be applied in the direction shown by the arrow through suitable means not shown. For example, a cable may be attached to hook 28 and may supply the necessary lifting force by a crane or a block and tackle arrangement not shown.

It should be noted, of course, that the shackle 24 may be constructed in various other ways and may comprise, for example, a U-shaped member providing a bight at its projecting end through which the hook 28 may be passed.

Figure 1 illustrates the situation wherein the plates to be lifted are stacked vertically, as on their edges. It is evident that when a vertical pull is applied to the shackle 24, ,the radius link therefore the greater the force required to lift it applied to shackle 24, the firmer is the grip on the steel plate, and the more securely is it retained between the cam I4 and the serrated gripping'pads I0. Moreover, the gripping force is applied instantaneously and positively, immediately upon application of lifting force at the end of the shackle 24.

` In the v iew shown in Fig. `2, plates which are stacked horizontally, as one on top of thefother, arelifted byfmeansof a verticalliiting pullapplied'at the end Vof shackle 24. .'.lrliislvievv'` illustrates the vutilityvof lmy'improved lifting clamp for lifting, not onlyV metal plates and similar thin-edged articles which are on 'edgel if., ai ranged vertically, but also for lifting thin-edged articles which may be arranged horizontally by means of the identical vertical pullV applied? to the end ofthe shackle24. VThe projectionorpro#` jecting portion 25 of the shackle- 24 "presses against the radius link I5, asjshown in' Fig. 2, when a pull' is applied-at the free fend of 'the shackle. This results in forcing theupper end of radius link I5 to theright in Fig. 2,'Ythis member rotating around its pivot i2;V Asa result the'connecting links I'I are forced to the right in Fig'. 2, thereby rotating 'caniv I4 in aA counterclookwise direction around-its pivot II, since the connect--` ing links VFlare-pivoter?. to the cam I4, at the pivot pin I9. The plate 9 is accordingly securely held in the slot 'I of the casing 4between the gripping pads I and the gripping surfaces I4a of the cam-I4. As increased'pull is applied to the `e'n'dof the shackle 24, itis evidentY thatthe plate 9 is held all theinore securely in thegslot l, thelgrippingforce being instantaneousand positive, and the'heavier'theload to be iifted,V the firmer is theV grip. `In this way thepla'te 9 or any other thin-edged element, 'maybe readily lifted from the horizontal position and transferred to a new position by means of a vertical pull at the end of the shackle. i j

It iis also evident thatA should plates or other thin-edged articles be stacked lin any position fri-1 termediate between the horizontal Yand vertical; my improved lifting clamp will function in the same way. Thegplates Vare securely retainedin the slot 'I and with increasedpull are all the more firmly retained therein between gripping surfacesy I4a of the vcam I4 and the gripping pads IIJ secured to the casing 4. `It is thus possible "to transfer such thin-edged elementsto a -newlocation by'means ofthe vertical .pull or'tension applied at theend of the shackle 24V by means'of a cable, rope, or otherwise. c .QQ

Even when lifting horizontal .platesthe pres-` suretransmitted `,by lug 25 causesserrations .to form on both sides-of the Aplate being lifted. Therefore, with the stationary jaw on one side the cam, as ,shown in Fig. 2, cannot be rotated clockwise to loosen the grip without breaking* the serrations in the plate on either the camp-side or theA iawf side..` ;.'1... loosen the er1, :requires manual action,and the plate is securely held until it is released by a hammerblow on the'endof the shackle 24. i A 1 A In the foregoing description, while'I have referred `to lifting plates which are stacked in vertical or horizontal positions, as illustrative of my invention, it is obvious that any other thinedged elements may be similarly'lifted.- It is also apparent that the lifting clamp is of very light and compact, yet rugged construction, and is capable of applying the gripping force instantaneously and positively to the member to'lbe lifted. Itis capable of handling material of any thickness, such Aas plates ranging vin sizev from the ythickness of thin sheets lup tov the thickness of thick armor plate. Thek gripping force applied to the thin-edged article between the cam I4 and the casing d, or between the gripping surfaces Ma of the cam i4 and the gripping pads l0 attached to and forming a part of the casing 4, is all the greater as the pull applied to the end of the shackle 2li is increased. The heavier the load to be lifted, the firmer is the thin-edged article held in the slot 'i of the casing 4.

While I have described one preferred embodiment of my invention, it is evident'that variations and modifications therein will be readily suggested to those skilled in the art. It is, accordingly, my intention that such variations and modifications, to the extent that they are within the scope of the appended claims, shall be considered a part of my invention.

I claim:

1. A lifting clamp capable of securely retaining thin-edged elements during a lifting operation wherein said elements are lifted fromeither a horizontal or vertical position, saidl clamp comprising: a supporting member provided with a gripping surface; a pivotally mounted cam secured in spaced relationship with said gripping surface, and adapted to coact with said gripping surface during a lifting operation, said cam being so shaped that, upon rotation thereof, said element to be lifted is securely retained between said cam and said gripping surface; a pivotally mounted radius link; a connecting link secured in pivotal relationship, at each end thereof, with said cam and said radius link; and a shackle pivotally attached to said radius link said shackle being provided with a projection which abuis against said radius link when horizontally positioned thin-edged elements are to be lifted, thereby causing said radius link and said cam to rotate, whereby a thin-edged element is securely retained between said cam and said gripping surface when a lifting force is applied to said shackle.

2. A lifting clamp capable of securely retaining thin-edged elements during a lifting operation wherein said elements are lifted from either a horizontal or vertical position, said clamp comprising: a casing provided with a slotted portion for the reception of a thin-edged element to be lifted; a pivotally mounted rotatable cam having a portion thereof projecting into said slotted portion of said casing; va rotatable radius link mounted for rotation within said casing; a connecting link pivotally connected at each end thereof with said cam and said radius link; and a shackle pivotally attached to said radius link and projecting outside of said casing, said shackle being provided with a portion thereof which abuts against said radius link when horizontally positioned thin-edged elements are to be lifted, thereby causing said radius link and said cam to rotate, whereby a thin-edged element is securely said casing during a liftingoperation to grip said thin-edged element to be lifted; a rotatable radius link mounted for rotation within said casing; Ia

' connecting link pivotally connected at each end thereof with said cam and said radius link;and-a` shackle lpivotallyattached to said-radius link, said shackle being provided with a -portion thereof which abuts against said radius link when horlzontally positioned thin-edged elements are to be lifted, thereby causing said radius link and said cam to rotate, whereby a thin-edged element is securely retained between said cam and said abutment portion of said casing when a lifting force is applied to said shackle.

4. A lifting clamp capable of securely retaining thin-edged elements during a lifting operation wherein said elements are lifted from either a horizontal or vertical position, said clamp comprising: a casing provided with a slotted portion for the reception of a thin-edged element to be lifted; a plurality of pivot pins positioned within said casing; a rotatable cam having a portion thereof projecting into said slotted portion of said casing positioned within said casing, said cam being mounted for rotation on one of said pivot pins; a rotatable radius link positioned within said casing and mounted for rotation on another of said pivot pins; a connecting link pivotally connected at each end thereof with said cam and said radius link; and a shackle pivotally attached to one end of said radius link and projecting outside of said casing, said shackle being provided with a projection which abuts against said radius link when horizontally positioned thin-edged elements are to be lifted, thereby causing said radius link and said cam to rotate, whereby a thin-edged element is securely retained in said slotted portion of said casing when a lifting force is applied to said shackle.

5.I A lifting clamp capable of securely retaining thin-edged elements during a lifting operation wherein said elements are lifted from either a horizontal or vertical position, said clamp comprising: a casing provided with a slotted portion for the reception of a thin-edged element to be lifted; a gripping pad secured to said casing adjacent said slotted portion; a plurality of pivot pins positioned within said casing; a rotatable cam having a portion thereof projecting into said slotted portion of said casing opposite said gripping pad, said cam being mounted for rotation on one of said pivot pins; a rotatable radius link positioned within said casing and mounted for rotation on another of said pivot pins; a connecting link pivotally connected at each end thereof with said cam and said radius link; and a shackle pivotally attached to one end of said radius link and projecting outside of said casing, said shackle being provided With a projection which abuts against said radius link when horizontally positioned thin-edged elements are to be lifted, thereby causing said radius link and said cam to rotate, whereby the thin-edged element to be lifted is securely retained in said slotted portion of said casing between said cam and said slipping pad when a lifting forceiis applied to said shackle.

6. A'llitingclamp capable ofsecurely retaining thin-edged elements during a fliftingcperation wherein said elements are lifted from either a horizontal or vertical position, said clamp comprising: a casing provided with a slotted portion for the reception of a thin-edged element Vto be lifted; a kgripping pad secured to said casing adjacent said kslottedportion; a plurality of pivot pins positioned within said casing; a rotatable cam having a portion thereof projecting into said slotted portion o said casing opposite said grip,` ping pad, said cam being provided with a serrated gripping portion coacting with said gripping pad to :ripa thin-edged element to be lifted, and beinxmounted for rotation on one of said pivot pins; 'a rotatable radius link positioned "within said casing and mounted for rotation on another of said pivot pins;l a connecting link pivotally connected at each end thereof with said cam and said radius link; and a shackle pivotally attached to one end of said radius link and projecting outside of said casing, said shackle being provided with a projection which abuts against said radius link when horizontally positioned thinedged elements are to be lifted, thereby causing said radius `link and said cam to rotate, whereby the thin-edged element to be `lifted is securelyt retained in said slotted portion of said casing. between said serrated gripping portion of said cam and said gripping pad. when a lifting forcev is applied to said shackle.

EDWARD MERRILL GARDNER. 

